1. Field of Invention
The present invention relates to an adaptive and all-optical method for data packet rate multiplication compatible with multiple data rates and/or multiple communication protocols, which enables rapid and real-time information processing capability and can meet requirements of ultrahigh-speed operations. In particular, the present invention relates to an ultrahigh-speed adaptive and all-optical method for data packet rate multiplication compatible with multiple data rates.
2. Description of Prior Art
With the popularization of Internet as well as the constant growth of demands on multimedia communications and wideband services, various communication protocols and standards, such as ATM, SDH, various Ethernet protocols, and Fiber Channel protocol, have been established or improved. This brings great challenges to the design of communication networks and systems, since the designed communication networks/systems should be adaptively compatible with all types of existing communication protocols and standards. Also, it is desirable that these designs can flexibly support the application of any future communication protocol/standard and system upgrade.
However, for users with different rates and protocols, all of the current Internet and telecommunication systems process data packets (hereinafter, “data packet” is referred to as “packet”) for transmission and exchange in the form of electronic signal, while transmit these packets in the form of optical signal. The specific steps comprise:
1) under the requirements of different communication protocols, such as ATM, SDH, various Ethernet protocols, and Fiber Channel protocol, processing the original user data or data from a communication network interface unit in the form of electronic signal, and packaging the data into electronic packets with a specified rate according to the specification of packet frame structure in the related communication protocol;
2) transmitting directly the packaged electronic packets via a cable, or transmitting optical packets obtained through electronic-to-optical (referred to as EO hereinafter) conversion from the electronic packets while maintaining the original frame structure and rate of the electronic packets;
3) if conversion between different data rates is required at some nodes of an optical network, performing the rate conversion in the electronic domain after the optical packets have been optical-to-electric (referred to as OE hereinafter) converted into electronic packets, and then conducting further communication after an EO conversion at the same rate.
The above method has a major drawback in that the packaging of electronic packets, EO conversion and OE conversion must be implemented in the electronic domain. However, the operating speed and bandwidth of most electronic devices and circuits are lower than those of optical devices, which leads to the problem of limiting the transmission rate of any communication network having signals processed in the electronic domain. This becomes a bottleneck for the transmission rate of such optical communication networks. For example, at present, the commercialized SDH optical fiber system has the highest rate of 40 Gb/s, while the maximum rate reaches only 10 Gb/s for a single wavelength in the commercialized optical Ethernet network. Although the identical-rate EO/OE conversion has been applied to such commercialized optical fiber transmission systems and communication networks as SDH system, Ethernet network, and dense WDM (DWDM) system/network, none of the optical fiber communication networks with electronic signal processing scheme can satisfy the rapid growing demand on IP data service due to the restriction of electronic bottleneck. Thus, none of them can support the increasing communication rate over the network. In addition, the adoption of such identical-rate EO/OE conversion limits the scalability of network and compatibility with any future ultrahigh-speed communication protocol.
With the commercialization of 40 Gb/s optical transmission systems and the study on 160 Gb/s optical communication systems, an ultrahigh speed and capacity communication network of all-optical transparent transmission and exchange, i.e., all-optical internet in a narrow sense, has become a target of future internet development. Since different end users or network interface devices may require different bandwidths and rates, one of the kernel techniques in designing an ultrahigh-speed all-optical internet is to realize an all-optical multi-rate interface so as to be adaptively compatible with user data of various rates. Such technique will have immediate effect on network scalability and operation flexibility. Currently, the following difficulties still exist in the realization of an ultrahigh-speed all-optical internet.
1) The low-rate optical packets need to be converted into optical packets at an ultrahigh rate and then be transmitted and exchanged. This requires a few, dozens or even thousands of times multiplication on the rate of the optical packets.
2) If the end users or network interface devices use different communication protocols, these different protocols must be complied with during the ultrahigh-speed multiplication of the optical packet rate. Further, the original frame structure in each communication protocol must be maintained after the rate multiplication.
3) If the end users or network interface devices each have optical packets of a different rate, compatibility must be considered during the ultrahigh-speed rate multiplication to transform various low-rate optical packets to the ultrahigh-rate optical packets required by the communication network.
4) All of the above processes must be adaptive.